1. Field of the Invention
The present invention relates to a negative refraction photonic crystal lens designed in accordance with the negative refraction characteristic of a photonic crystal structure.
2. Description of Related Art
In accordance with the progresses of high-tech industries and for the purpose of improving efficiencies and qualities of products, processes for fabricating the products are developed toward miniaturization. For example, all of the 30 nm and 45 nm linewidth processing of the semiconductor industry, tiny defects on the panel surface of the flat panel display (FPD) industry, and surface defects of the precision optical element industry should be inspected. Correspondingly, small inspection equipment having a high resolution is highly demanded. During the fabrication processes of the products, even very tiny processing defects or contaminants may seriously destroy the yield and performance of the products. Particularly, very low defect density may negatively affect subsequent processing stages and cause incurable damage to the quality of an epitaxial wafer or an FPD substrate.
There are different kinds of defect inspection tools provided in the market. However, they are often expansive, complex in operation, and occupy large spaces. These defect inspection tools usually have relatively low resolutions which are insufficient for complying with the requirement for nano-scale inspection and online instant inspection. Specifically, for example, with respect to the optical inspection technology for inspecting a surface of an object, an optical lens is often a critical component. However, the current optical lenses are often featured with unsatisfactory imaging performances and insufficient optical resolutions.